The number of concurrent users on Wolverine Access and CTools peaked at levels significantly higher than previous record-usage days. That increase in concurrent users exposed a software bug that crippled the system on the first day of classes.

"Since we never had reached this level of usage before, the bug had gone unexposed," said Laura Patterson, chief information officer and head of Information and Technology Services.

"We have added more hardware to the Wolverine Access environment to keep the usage per-server at a lower level until we get through the rush of the start of the term. After we get past the rush, we will upgrade the software to fix the bug. We also have added more hardware to the CTools environment to get us safely through this busy time of year," Patterson said.

ITS teams worked continuously Tuesday to get the website up and running. Access was restored about 6 p.m.

While the investigative work continues today, Patterson said ITS would continue to make the direct links to systems available on the U-M Gateway.

"We know this was especially inconvenient and challenging for students and faculty on the first day of classes, and our whole team is sorry for the significant disruption," Patterson said.